Load height indication

ABSTRACT

Unseen loads on a tower crane are stopped at desired levels by an operator who is stationed at a location where the load cannot be seen. A rotation measuring device is mounted on the load cable winding drum. Gears between the drum and measuring means rotate the measuring means at a fixed number of turns per linear foot of the winding drum. A telemetering system turns a synchronous motor at the operator&#39;&#39;s control station, and the synchronous motor turns an indicator to display the load position in numbers of feet from a reference point.

United States Patent 1 Ancheta 1 1 LOAD HEIGHT INDICATION [76] Inventor: Edward F. Ancheta, 2244 Jennie St., Honolulu, Hawaii 96819 [22] Filed: Dec. 29, 1972 21 Appl. No.: 319,746

[52] US. Cl. 340/267 C; 212/39 R [51] Int. Cl. B66c 13/46 [58] Field of Search 340/267 C, 177 R, 198;

[56} References Cited UNITED STATES PATENTS 2,565,951 8/1951 Crookston et a1. 73/151.5

3,199,685 8/1965 Bopp 340/267 C 3,545,725 12/1970 Chandler 254/173 R 3,562,740 2/1971 Watkins 340/198 3,724,679 4/1973 Brownell et a1 340/267 C [4 1 May 13, 1975 7/1973 Lute 340/267 C 3/1974 Cording 254/173 R Primary Examiner-Glen R. Swann, Ill Attorney, Agent, or Firm-James C. Wray [57] ABSTRACT Unseen loads on a tower crane are stopped at desired levels by an operator who is stationed at a location where the load cannot be seen. A rotation measuring device is mounted on the load cable winding drum. Gears between the drum and measuring means rotate the measuring means at a fixed number of turns per linear foot of the winding drum. A telemetering system turns a synchronous motor at the operators control station, and the synchronous motor turns an indicator to display the load position in numbers of feet from a reference point.

5 Claims, 5 Drawing Figures PATENTED RAY I 31975 1.883 859 saw 2 BF 3 LOAD HEIGHT INDICATION BACKGROUND OF THE INVENTION Tower cranes are well known and widely used in the construction of multiple floor buildings. The convenience of a single crane to which any part of the construction is accessible and to which no part of any building, apron, sidewall or top is unreachable has resulted in widespread use of the cranes. The value of the cranes is evidenced in part by the wide use of the cranes, which are visible in any city where construction is prominent. The value placed upon the cranes, which are known as tower cranes, is further evidenced by the fact that their operators command some of the highest wages paid in the construction industry. The high esteem of the crane operator is due not only to the great value of the tower cranes in speeding construction and saving construction costs but also is based on the great skill required to overcome the difficulties of operating the cranes. One of the great difficulties that remains in the operation of tower cranes is the extreme difficulty and often inability of the operator to judge the precise position of the load. It is that difficulty which this invention is designed to overcome.

Several different types of tower cranes are in use today. In some of those tower cranes, the operators enclosure is mounted directly within the central supporting column of the crane. In other types of cranes, the operators platform is supported on the central column but is cantilevered off to one side. In other tower cranes, the operators station may be a relocatable bench for positioning on the uppermost completedfloor, or a body supported panel which the operator may carry as he walks. In the latter types, the bench or panel is connected to the crane by a long, flexible umbilical cord.

In the mobile types of control units, an operator may be stationed near the edge of an upper floor so that he can see down along the side of a building to the building apron area on which materials are off-loaded for temporary storage. The operator may be able to see the load or load-engaging hook and may be able to perceive its distance from the desired stopping point. Even under conditions of direct visibility, it is difficult to precisely perceive load position, and the alertness of a hand signalling helper must be greatly relied upon. Often the upper floor of a building under construction is surrounded by a projecting retainer lip which prevents direct visual communications between a crane operator at a mobile station and loads at the building apron. The crane operator must then place his reliance upon a radio man who can see the load-engaging hook and the load. Reliance upon a radio man is usually always necessary when the operator is stationed in a fixed enclosure on the main supporting column of the crane.

When the operator cannot see a load, he depends 100% upon the radio man for starting and stopping, raising and lowering, running and inching commands.

The radio operator is usually positioned in an area of heavy traffic and activity. The possibilities for distractions are great. When a load of a heavy weight is being lowered at a substantial speed, it is possible for a radio operator to become distracted and to have-the load impact the ground at a rate of speed which creates dangers to the load, to its surroundings and to nearby persons. The crane operator has a helpless feeling with his hands on controls ofa moving load which he cannot see and which he cannot be absolutely sure someone else is watching.

A need has long existed for some device which presents to the operator in convenient display the exact position of a load with reference to a fixed plane, for example, the ground.

SUMMARY OF THE INVENTION The present invention comprises a load height indicator for a tower crane to indicate to the operatorof a crane the precise or approximate position of a load with respect to a fixed reference plane.

The invention resides in the combination of a tower crane which has a column or mast extending upward from a base through a building under construction and usually in the center of the building. On top of the column, a rotatable, generally horizontal boom or jib is mounted. The jib usually extends unequally in opposite directions with the longer portion extending outward and projecting beyond the furthermost portion of the building under construction. The long end usually outwardly terminates in a sheave whose function will later be described. The short oppositely extending jib usually supports counterweights and usually supports the main hoisting apparatus, which includes a heavy duty electric motor and gearing to drive a hoisting drum on which a hoisting cable is wound. The hoisting apparatus may be supported outwardly on the short jib or inward near the central supporting column. A carriage or trolley is mounted on rails beneath the long jib. Driving means moves the trolley inward and outward along the jib. The driving means may, for'example, comprise a cable connected to the trolley and suspended over pulleys at opposite ends of the long arm of the jib and move by a reversible electric motor driven winch. Alternatively, the cable may be driven unidirectionally, and grippers on the trolley may grip one strand of the cable or the other for inward or outward movement. Alternatively, a rack may be mounted along one rail and may be engaged by a pinion which is driven by a reversible electric motor on the trolley.

A hoisting cable is wrapped around the hoisting drum and extends upward to a slideable and rotatable pulley at the top of an upwardly extending cone, which is mounted on the rotatable jib structure above the central fixed column. The hoisting cable then passes from the pulley to the sheave at the outward extremity of the jib and back beneath the jib to a first pulley on the trolley. The cable then extends downward to a sheave on a load-engaging hook and then upward to a second pulley on the trolley. The cable then extends inward beneath the jib to an anchor near the inward extremity of the jib. As the trolley is moved inward and outward along the jib, the distance of the load book from the trolley is unaffected.

A device of the present invention in this combination measures the cable deployment from the drum. -It is measured by a selsyn transmitter connected by appropriate gearing to the drum. Wires connect the selsyn transmitter to a selsyn motor which is directly coupled to a numerical indicator at the operators station. The operator then has a direct indication in terms of numbers of feet of the load from the reference plane.

Broad objectives of this invention are accomplished by the provision of load height measuring apparatus in a tower crane. A further object of this invention is the provision of a drum revolution reversible counting and telemetering device for indicating cable winding drum revolution in terms of one-half of the feet of cable deployed on an indicator in a tower crane operators enclosure.

These and other objects and features of the invention are apparent in this disclosure, which includes the drawings and the specification, with the claims which are a part thereof.

DESCRIPTION OF THE DRAWINGS FIG. 1 is a schematic representation of a tower crane mounted on a building and showing the situation in which a load is beyond the view of the crane operator.

FIG. 2 is a schematic representation of a device for indicating position of the load.

FIG. 3 is a schematic representation of the transmitting portion of the telemetering system which transmits signals related to load height.

FIG. 4 is a schematic view of the further measuring system for determining cable position.

FIG. 5 is a schematic representation of the reverse side of apparatus shown in FIG. 4 and of an indicating means associated with the measurement means of FIG.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS In FIG. 1 a building is generally indicated by the numeral 1. A portion of the building has been cut away to show the tower crane which extends downward into the building. The crane extends out beyond a corner 5 of the building and extends over the uppermost floor 7 which is completed. A tower crane generally indicated by the numeral 9 has ajib 10 which terminates outward in a sheave 12. A cable hoisting system is mounted on the opposite end of a short jib, near counterweights. In other tower cranes, the hoisting system may be mounted inward near the vertical tower or column. As hoisting means 15 is turned, load 17 is raised and lowered according to the direction of turning.

A crane operator 20 is stationed in a cabin 23 which is mounted near the vertical column 25. In some cranes, the operators cabin 23 is connected to the upper structure for turning with the jib. As shown in the drawing, a sliding pulley supports the load lifting cable 27 as it runs from winding drum 15 outward along the jib l0 and around sheave 12. Cable 27 continues inward over a first pulley in trolley 28 and downward to a pulley 29 on a load engaging hook, then upward and around a second pulley on trolley 28 and then inward to an anchor near the innermost extremety of the jib. Trolley 28 moves inward and outward beneath the jib along rails, propelled by a conventional power source which is not shown. The operator 20 controls a reversible electric drive 31 to turn winding drum 15 and to raise and lower load 17. Usually, the load is in the space generally indicated by the numeral 32 where it is beyond the visibility of the operator. The operator must rely upon others'without knowing the precise load position above the ground.

FIGS. 2 and 3 show a telemetering system for indicat ing load position as a function of cable deployed on the winding drum. As shown in FIG. 3, a cable hoisting system generally indicated by the numeral 15 comprises an axle 38 which turns with a winding drum 40.-Cable 42 is wound on the drum or released from the drum to raise or lower a load. As shown in the drawings, gear 43 is mounted on an extended end 44 of the shaft 38 which rotates with the drum 40. Gear 43 drives gear 45 mounted on shaft 46 of an A-end or transmitting portion of a telemetering device indicated by the numeral 48A. Device 48A drives device 48B in a like direction and amount. As an example, the telemetering devices used in the present system as Selsyn generators and motors. Communication and power wires 50, 52, 54, 56 and 58 connect Selsyn generator 48A with Selsyn motor 488. A coupling 62 connects the shaft of Selsyn motor 48B to the shaft of a reversible mechanical counter 64. Counter 64 indicates the position of the load in tenths of feet. The gearing between the cable winding drum and the Selsyn generator is configured so that the generator will make one turn upon the winding of 2 feet of cable on or off the winding drum, which causes a corresponding one foot movement of the load.

An alternate telemetering system is shown by way of example in FIGS. 4 and 5. Drum winds cable 72 which passes through a metering device 75. A pinch roller 76 is mounted on an axle 77 which is supported by pivot 79 and arm 80. A pulley 82 which may have grooves to ensure against cable slippage is mounted on an axle 83. In the present case, the pulley 82 may be a separate device or may be the pulley which is the uppermost pulley 26 on the crane or the sheave 12 at the end of the jib.

As shown in FIG. 5, the pinch roller arm is held downward against the pulley by a spring which is connected to a fixed lug 91 and to a lug which extends from arm 80 through opening 85. As shaft 83 turns one complete revolution, disc 92 causes lug 93 to push throw 94 against pole 95, completing a circuit in conductors 96, 99 and 101 between power source 100 and electronic counter 102. When pulley 82 and shaft 83 turn in the opposite direction, throw 94 is moved oppositely to instantaneously connect the circuit of conductors 97, 99 and 101 for driving counter 102 in the opposite direction.

Using the telemetering system of the present invention, a crane operator who is lowering a load may stop a load befo e it hits the ground notwithstanding possible inattentiveness of a signalman who fails to request a slowing down and stopping of a load.

Although the invention has been describedin part with reference to specific examples, it will be obvious to one skilled in the art that modifications can be made without departing from the invention. The scope of the invention is described in the following claims.

- I claim:

1. Load height indicating apparatus for tower cranes having a base, a column extending upward from the base, a jib extending horizontally from the column and mounted for rotation on the column, rotating means connected to the jib and to the column for rotating the jib on the column, a trolley mounted on the jib for selectively positioning on the jib, propellingmeans connected to the jib and to the trolley for moving the trolley on the jib, hoisting means connected to the trolley for lifting loads,.and load engaging means connected to the hoisting means for engaging and holding loads on the hoisting means below the trolley, and control means connected to the rotating means, to the propelling means and to the hoisting means for separately controlling those means, the improvement comprising measuring means connected to the hoisting means for determining the condition of the hoisting means and thus determining position of the load engaging means with respect to the trolley, telemetering means connected to the measuring means for telemetering condition of the measuring means, and indicator means connected to the telemetering means and mounted near the control means for indicating condition of the measuring means and hence position of the load.

2. The load height indicating apparatus of claim 1 wherein the hoisting means comprises a winding drum and power means for operating the winding drum, a cable Wrapped around the drum and extending over the jib to the trolley, extending downward from the trolley to the load engaging means and upward from the load engaging means to the trolley, and extending along the jib to an anchor, and wherein the measuring means comprises means for measuring cable deployed from the drum.

3. The load height indicating apparatus of claim 2 wherein the measuring means comprises means for measuring rotational movement of the drum.

4. The load height indicating apparatus of claim 3 wherein the measuring means comprises a gear connected to the drum, a second gear in engagement with the first gear and wherein the telemetering means comprises a generating means connected to the second gear for generating a signal as the second gear turns, transmission means connected to the generating means for transmitting the signal from the generating means, motor means connected to the transmission means for movement in response to the signal from the transmission means, and wherein the indicator means comprises a reversible counter connected to the motor means.

5. The load height indicating apparatus of claim 4 wherein the generating means and motor means comprise Selsyn motors and wherein the transmission means comprises electrical communication means. 

1. Load height indicating apparatus for tower cranes having a base, a column extending upward from the base, a jib extending horizontally from the column and mounted for rotation on the column, rotating means connected to the jib and to the column for rotating the jib on the column, a trolley mounted on the jib for selectively positioning on the jib, propelling means connected to the jib and to the trolley for moving the trolley on the jib, hoisting means connected to the trolley for lifting loads, and load engaging means connected to the hoisting means for engaging and holding loads on the hoisting means below the trolley, and control means connected to the rotating means, to the propelling means and to the hoisting means for separately controlling those means, the improvement comprising measuring means connected to the hoisting means for determining the condition of the hoisting means and thus determining position of the load engaging means with respect to the trolley, telemetering means connected to the measuring means for telemetering condition of the measuring means, and indicator means connected to the telemetering means and mounted near the control means for indicating condition of the measuring means and hence position of the load.
 2. The load height indicating apparatus of claim 1 wherein the hoisting means comprises a winding drum and power means for operating the winding drum, a cable wrapped around the drum and extending over the jib to the trolley, extending downward from the trolley to the load engaging means and upward from the load engaging means to the trolley, and extending along the jib to an anchor, and wherein the measuring means comprises means for measuring cable deployed from the drum.
 3. The load height indicating apparatus of claim 2 wherein the measuring means comprises means for measuring rotational movement of the drum.
 4. The load height indicating apparatus of claim 3 wherein the measuring means comprises a gear connected to the drum, a second gear in engagement with the first gear and wherein the telemetering means comprises a generating means connected to the second gear for generAting a signal as the second gear turns, transmission means connected to the generating means for transmitting the signal from the generating means, motor means connected to the transmission means for movement in response to the signal from the transmission means, and wherein the indicator means comprises a reversible counter connected to the motor means.
 5. The load height indicating apparatus of claim 4 wherein the generating means and motor means comprise Selsyn motors and wherein the transmission means comprises electrical communication means. 